The Senate’s majority leader buried provisions in the massive US$1.1 trillion end-of-the-year spending bill that will prevent watchdogs from investigating political spending of companies and imposing regulations on ‘dark money’ groups.

The new bill prevents the Securities and Exchange Commission (SEC) from implementing any “order regarding the disclosure of political contributions, contributions to tax exempt organizations or dues paid to trade associations,” the bill says.

The IRS have also been targeted in the bill, and are now unable to issue a rule in 2016 regarding the level of nonprofit organizations political activity. Advocates for financial reform argue that the current system allows American elections to be bought by ‘dark money’ and ‘anonymous’ donors.

‘Dark money’ refers to the funds given to nonprofit organizations that can receive unlimited donations from corporations, individuals and unions, and spend their funds to influence elections, but are not required to disclose their donors.

McConnell has been a continuous advocate of unlimited secret campaign spending in Washington, often citing free speech as the reason.

The senior Kentucky senator’s own campaign has benefited from US$23 million of ‘dark money’ from independent groups like the National Rifle Association and the Nation Federation of Independent Business.

“Spending by organizations that do not disclose their donors has increased from less than US$5.2 million in 2006 to well over US$300 million in the 2012 presidential cycle and more than US$174 million in the 2014 midterms,” according to the Center for Responsive Politics.

For example, the Conservative Solutions Project has run more than 4,882 ads in support of Republican presidential hopeful Marco Rubio, and not a dime of its funding has been made public, reported Mother Jones.

The nonprofit organizations are, in theory, regulated by the IRS, but because of the new legislation McConnell introduced, the IRS can’t investigate the people or corporations who finance campaigns like Rubio’s run for presidency.

Historically, traditional political action committees (PACs) had strict limits on how much businesses, nonprofits and individuals could give. But a landmark 2010 Supreme Court ruling opened the door for unlimited amounts of cash to be donated to influence campaigns, because restricting this behavior would be akin to restricting what people can say, violating the First Amendment.

This isn’t the first move the majority leader has made to push his secret spending agenda. In last year’s budget he pushed through higher limits for campaign contributions to party organizations, making way for wealthy donors to give hundreds of thousands of dollars.

Mitch McConnell is flooding our elections with dark money & will eliminate one of the only campaign finance regulations left.

McConnell tried again to remove limits on how party committees spend money during this year’s budget negotiations, but stood down after he received heavy opposition from Democrats, some Republicans and campaign finance reformers, reported The Hill.

"We do feel good about what we did get and would love to have achieved more. And it's going to take a new president of a different party to achieve what we'd like to achieve,” McConnell said to the Associated Press when speaking about the bill.

At a 2010 DNC rally, President Obama said that special interest groups that pour money into attack ad campaigns without ever having to disclose their spending are “a threat to our democracy.” In July of this year, it was reported Obama was considering an executive order to require all federal contractors to disclose their dark money spending.

"The president is pleased with the final product, even if it does reflect the kind of compromise that's necessary when you have a Democratic president negotiating with large majorities of Republicans," said press secretary Josh Earnest after Obama signed off of the latest budget bill.